Umbilical mesenchymal stem cell-derived exosomes facilitate spinal cord functional recovery through the miR-199a-3p/145-5p-mediated NGF/TrkA signaling pathway in rats

• Published in: Stem cell research & therapy Vol. 12; no. 1; p. 117
• Main Authors: Wang, Yang, Lai, Xunwei, Wu, Depeng, Liu, Bin, Wang, Nanxiang, Rong, Limin
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 12.02.2021; BioMed Central; BMC
• Subjects: AKT protein; Axonogenesis; Cell differentiation; Chromosome 5; Ethics; Exosomes; Experiments; Inflammation; Kinases; Laboratory animals; Lipopolysaccharides; Medical research; Mesenchymal stem cells; MicroRNA; microRNAs; Mitogens; Morphology; Nanoparticles; Nerve growth factor; PC12 cells; Pheochromocytoma cells; Proteins; Recovery of function; Signal transduction; Spinal cord; Spinal cord injuries; Spinal cord injury; Standard deviation; Statistical analysis; Stem cell research; Stem cell transplantation; Stem cells; Transmission electron microscopy; Transplantation; TrkA protein; TrkA receptors; TrkA ubiquitination; Ubiquitin; Ubiquitination; Umbilical cord; Umbilical cord mesenchymal stem cells; Variance analysis; United Kingdom > UK; United States > US; China; microRNAs; Umbilical cord mesenchymal stem cells; TrkA ubiquitination; Exosomes; Spinal cord injury; PC12 cells
• ISSN: 1757-6512; 1757-6512
• DOI: 10.1186/s13287-021-02148-5

Although exosomes, as byproducts of human umbilical cord mesenchymal stem cells (hUC-MSCs), have been demonstrated to be an effective therapy for traumatic spinal cord injury (SCI), their mechanism of action remains unclear. We designed and performed this study to determine whether exosomes attenuate the lesion size of SCI by ameliorating neuronal injury induced by a secondary inflammatory storm and promoting neurite outgrowth. We determined the absolute levels of all exosomal miRNAs and investigated the potential mechanisms of action of miR-199a-3p/145-5p in inducing neurite outgrowth in vivo and in vitro. miR-199a-3p/145-5p, which are relatively highly expressed miRNAs in exosomes, promoted PC12 cell differentiation suppressed by lipopolysaccharide (LPS) in vitro through modulation of the NGF/TrkA pathway. We also demonstrated that Cblb was a direct target of miR-199a-3p and that Cbl was a direct target of miR-145-5p. Cblb and Cbl gene knockdown resulted in significantly decreased TrkA ubiquitination levels, subsequently activating the NGF/TrkA downstream pathways Akt and Erk. Conversely, overexpression of Cblb and Cbl was associated with significantly increased TrkA ubiquitination level, subsequently inactivating the NGF/TrkA downstream pathways Akt and Erk. Western blot and coimmunoprecipitation assays confirmed the direct interaction between TrkA and Cblb and TrkA and Cbl. In an in vivo experiment, exosomal miR-199a-3p/145-5p was found to upregulate TrkA expression at the lesion site and also promote locomotor function in SCI rats. In summary, our study showed that exosomes transferring miR-199a-3p/145-5p into neurons in SCI rats affected TrkA ubiquitination and promoted the NGF/TrkA signaling pathway, indicating that hUC-MSC-derived exosomes may be a promising treatment strategy for SCI.